Before I say anything in this post, I just want to address this directly to you and anyone who reads this who does not already know:
Your information (including your private emails, your personal files, your social network accounts and so on) are never guaranteed to be 100% secured. There is always a possibility that a company storing your information (account credentials/information, such as: usernames, passwords, bank details) can be hacked. There is always a possibility your Anti-virus/Anti-malware product will miss a sample which causes harm: including breach of your data (privacy, generally speaking), causes system instability and so on. Of course, system instability, BSOD crashes, or worse, can prevent you from accessing your data (if it corrupts something). On that note, samples like cryptolocker will encrypt your files. So just remember, no matter what
you can never be 100% safe whilst using a computer, you can only take actions to improve your protection to be more "safe".
Therefore, there is not a fullproof "secure" and "safe" email client. I would have thought gmail was secure enough, for me at least.
I'm not 100% certain as to what you are asking for (e.g. a desktop client to view your email, or another web based service like gmail, yahoo and hotmail), however you could try one of the following desktop email clients:
Whether they are "secure" and "safe" to use, I do not know. I am sure other members on the forum could help you with email clients - I don't really use email clients for desktop. I use the web-based gmail service
- Microsoft Outlook (go for the latest version, 2013)
- Thunderbird
Cheers.